The $substrBytes operator uses the indexes of UTF-8
encoded bytes where each code point, or character, may use between one
and four bytes to encode.

For example, US-ASCII characters are encoded using one byte. Characters
with diacritic markings and additional Latin alphabetical characters
(i.e. Latin characters outside of the English alphabet) are encoded
using two bytes. Chinese, Japanese and Korean characters typically
require three bytes, and other planes of unicode (emoji, mathematical
symbols, etc.) require four bytes.

It is important to be mindful of the content in the
stringexpression because providing a byteindex or
bytecount located in the middle of a UTF-8 character will result
in an error.

The following operation uses the $substrBytes operator
separate the quarter value (containing only single byte US-ASCII
characters) into a yearSubstring and a quarterSubstring. The
quarterSubstring field represents the rest of the string from the
specified byteindex following the yearSubstring. It is
calculated by subtracting the byteindex from the length of the
string using $strLenBytes.